JP2010119045A - Antenna device, and radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent angle measuring accuracy from being degraded without being influenced by manufacturing accuracy. <P>SOLUTION: This antenna device includes: a plurality of sub-array antennas 101 each including a plurality of antenna elements 102; and a plurality of power feed parts 104 each of which is connected to an end of the plurality of sub-array antennas one-by-one. The plurality of sub-array antennas 101 are arranged side by side on the same plane parallel to one another at intervals not larger than a free space wavelength and, with respect to a center axis parallel to the plurality of sub-array antennas 101 on the same plane, bisecting the total number of the plurality of sub-array antennas 101, and dividing them into two sub-array antenna groups, the sub-array antenna groups are in a mirror image relationship with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an array antenna, and more particularly to an antenna device and a radar device having a plurality of feeding ports.

There is an array antenna in which a plurality of subarray antennas are arranged for the purpose of digital beam forming, beam scanning, or monopulse system (see, for example, Non-Patent Document 1). In the millimeter wave band, there are triplate line patch antennas, microstrip line patch antennas, horn antennas, waveguide slot array antennas, etc. as antenna elements used for subarray antennas. Power is supplied by a strip line, a triplate line, a waveguide, a post wall waveguide, or the like (see, for example, Patent Document 1 or Non-Patent Document 2). The feed port of the sub-array antenna is generally a waveguide feed in a millimeter wave on-vehicle radar. Some array antennas effectively utilize the aperture area by arranging the transmitting and receiving antennas in an interdigital structure and feeding power from both sides (see, for example, Non-Patent Document 3).
JP 2000-124727 A "Antenna Engineering Handbook (Second Edition)", Ohmsha, p339-p445 Iizuka et al., “In-vehicle millimeter-wave radar antenna”, 2001 IEICE General Conference, SB-1-7, p743-p744. Yusuke Okajima, Park Seijou, Jiro Hirokawa, Makoto Ando, “Orthogonal 45 Degree Polarization Shared Post-Wall Waveguide Slot Array Using Interdigital Structure” IEICE Technical Report, A / P2003-149, RCS2003-155, pp . 21-26

When horizontal angle measurement is performed like in-vehicle radars, subarray antennas are arranged in the horizontal direction, and feed openings are provided in the respective subarray antennas. The distance between the subarray antennas is in balance with the grating lobe level, and it is necessary to reduce the distance between the subarray antennas in a radar aiming at widening the angle. For example, assuming that the maximum scanning angle is 40 degrees, if the free space wavelength of the operating frequency of the subarray antenna is defined as λ ₀ , it is necessary to select about 0.6λ ₀ or less. In yet waveguide feed, when the feed ports of the sub-array antennas are formed on the same side, the wide wall from the relationship of the waveguide cutoff is required 0.5 [lambda ₀ or more, and the metal forming the waveguide Considering physical influences such as wall thickness and choke structure for improving the isolation between the feeding ports of each antenna, a space exceeding the condition for suppressing the grating lobe level is required. Therefore, the width of the power feeding part of the antenna becomes wider than the radiation part of the antenna, and the area of the whole antenna becomes large.

  As an improvement method, there is a method of feeding power to the antenna from above or below or from the left and right, and the aperture area of the transmitting and receiving antenna can be used effectively.

  However, although physical influences on the structure can be avoided, the interdigital structure is asymmetric with respect to the beam scanning surface, so the feed phase to each port is shifted asymmetrically due to the influence of manufacturing accuracy, etc. The point tilts asymmetrically, and the monopulse method has a problem that the angle measurement accuracy is impaired.

  The present invention has been made to solve the above-described problems, and provides an antenna device and a beam device that do not depend on manufacturing accuracy and do not impair angle measurement accuracy.

  In order to solve the above-described problem, an antenna device according to the present invention includes a plurality of subarray antennas each including a plurality of antenna elements, and a plurality of power feeding units connected respectively to end portions of the plurality of subarray antennas. The plurality of subarray antennas are arranged in parallel on the same plane at intervals of a free space wavelength or less, parallel to the plurality of subarray antennas on the same plane, and all of the plurality of subarray antennas. The subarray antenna groups are in a mirror image relationship with respect to a central axis that is divided into two equal parts and divided into two subarray antenna groups.

  The antenna device according to the present invention includes a plurality of subarray antennas each including a plurality of antenna elements, and a plurality of power feeding units that respectively feed power to the plurality of subarray antennas. The plurality of subarray antennas are arranged in such a manner that the plurality of subarray antennas are arranged in parallel on the same plane with respect to the alignment direction of the plurality of antenna elements so that an interval between adjacent subarray antennas is equal to or less than a free space wavelength. And the sub-array antenna groups are mirror images of each other with respect to a central axis that divides the total number of the plurality of sub-array antennas into two equal parts and divides them into two sub-array antenna groups. In each of the third subarray antennas, which are subarray antennas closest to the central axis. The fourth feeding section of the adjacent fourth sub-array antenna is connected to the end of the fourth sub-array antenna at the farthest distance from the third feeding section, and sequentially adjacent to the third feeding section of the antenna. A feed section is connected to the subarray antenna in an interdigital manner.

  Furthermore, a radar apparatus according to the present invention includes an antenna including a plurality of subarray antennas each including a plurality of antenna elements, and a plurality of power feeding units connected to end portions of the plurality of subarray antennas, respectively, and the antenna. An RF chip unit that performs processing including amplification of the received signal and down-conversion to frequency-convert the signal to obtain a converted signal; an analog-to-digital converter that performs analog-to-digital conversion on the converted signal and converts the signal into a digital signal; A monopulse DBF unit that estimates a beam arrival direction from a digital signal, and the plurality of subarray antennas are arranged in parallel on the same plane at intervals equal to or less than a free space wavelength, and the plurality of subarray antennas are arranged on the same plane. Parallel to the sub-array antenna and divide the total number of the plurality of sub-array antennas into two equal parts With respect to the central axis which divides into two sub-array antenna groups, the sub-array antenna groups each other, characterized in that a relationship of mirror image.

  According to the antenna device and the radar device of the present invention, the feeding ports of the sub-array antennas are not affected by the physical structure of each other, and the angle measurement accuracy is not impaired regardless of the manufacturing accuracy.

Hereinafter, an antenna device and a radar device according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same reference numerals are assigned to the same numbered parts, and repeated description is omitted.
First, an antenna device and a radar device according to an embodiment of the present invention will be described with reference to FIG.
The antenna device 100 according to the present embodiment includes a subarray antenna 101, an antenna element 102, a feed line 103, and a feed port 104. Furthermore, in the antenna device 100, an array antenna group is formed by arranging a plurality of subarray antennas 101 in parallel on the same plane as the direction in which the antenna elements 102 are aligned.
The subarray antenna 101 includes a plurality of antenna elements 102 and a feed line 103.
The antenna element 102 is constituted by, for example, a slot or horn when a waveguide structure is used, and a patch element when a microstrip line is used.
The feed line 103 includes, for example, a waveguide, a microstrip line, a triplate line, and a post wall waveguide, and feeds power to the antenna element 102.
The shape of the power supply port 104 changes depending on the shape of the power supply line 103 used for power supply. The power supply port 104 has a mode converter structure that matches the shape of the power supply line 103.

The distance d between the sub-array antennas 101 when the sub-array antennas 101 are arranged in parallel is (1) when the free space wavelength λ of the operating frequency of the sub-array antenna and the maximum scanning angle are θm in order to suppress unwanted radiation such as a grating lobe. It is necessary to satisfy the formula.

A plurality of subarray antennas 101 are arranged in parallel in parallel with the alignment direction of the plurality of antenna elements 102 so as to satisfy the equation (1). In particular, the subarray antennas 101 are arranged so that the interval between them is equal to or less than the free space wavelength. The plurality of subarray antennas 101 may be arranged so that the adjacent interval between the subarray antennas 101 is about 0.6λ or less so that side lobes can be suppressed when beam scanning of 40 degrees or more is performed. In FIG. 1, the number of subarray antennas 101 is eight. However, the number of subarray antennas 101 to be arranged is not limited and may be plural as long as there is a space to be applied. What is important in the arrangement of the subarray antenna 101 is that the subarray antenna 101 is arranged so as to have a mirror image relationship (line symmetry) with respect to the central axis of the antenna device 100. Specifically, when the number of subarray antennas 101 is an even number, a central axis is assumed between the two subarray antennas 101 at the center, and the same number of subarray antennas 101 exist on both sides as shown in FIG. Arrange as follows. When the number of subarray antennas 101 is an odd number, one subarray antenna 101 at the center is selected as the central axis as shown in FIG. 2, and the same number of subarray antennas 101 are arranged on both sides thereof.
For the subarray antennas 101 arranged in parallel to positions other than the center, the feeding ports 104 of the adjacent subarray antennas 101 are arranged at positions farthest from each other. In other words, as shown in FIG. 1, the subarray antenna 101 has a feeding port 104 at one end, and adjacent subarray antennas 101 are staggered so that the feeding port 104 is at the end opposite to the alignment direction of the subarray antenna 101. Take an interdigital structure. Here, when the total number of subarray antennas 101 is an even number, the feeding ports 104 of the two subarray antennas 101 that are closest to the central axis across the central axis are arranged adjacent to each other in order to maintain a mirror image.
At this time, the feed ports of the two sub-array antennas 101 at the center keep the positions of the feed ports so that the sub-array antennas 101 are kept at an interval equal to or smaller than the free space wavelength and the feed ports do not physically interfere with each other. It may be offset in the direction. The offset distance is shifted in the direction of the central axis by a distance that is equal to or greater than the difference between the shortest distance from the center of the power feeding unit of the subarray antenna in the center to the periphery of the power feeding unit in the direction of the central axis and half the interval. . Specifically, referring to FIG. 1, when the width of the waveguide is w and the interval between the subarray antennas is d,

As described above, for the subarray antenna 101 on the right side of the center, the feed line 103 is offset in the direction of the central axis, that is, on the left side. For the subarray antenna 101 on the left side of the center, the feed line 103 is offset to the right side. That is, the offset is performed so that the two subarray antennas 101 sandwiching the central axis approach each other. In FIG. 1, the description has been made on the assumption that waveguide feeding is performed, but other microstrip line-waveguide converters, triplate lines-waveguide converters, post-wall waveguide-waveguide converters. The same applies to power supply using other mode converters.
When the total number of subarray antennas 101 is an odd number, there are no feed ports 104 that are mutually adjacent, and feed ports 104 are alternately arranged at the farthest end of all adjacent subarray antennas 101.

Here, the relationship between mirror images, that is, the advantage of a left-right symmetric structure will be described with reference to FIGS.
For example, when the antenna device 100 according to the present embodiment is used as a radar device, it is conceivable to perform angle measurement using a monopulse method. An example of a radar apparatus that performs angle measurement by the monopulse method is shown in FIG. FIG. 3 shows a circuit at the time of monopulse reception. A radar apparatus 300 according to this embodiment includes antennas 301a, 301b, 301c, and 301d, an RF chip unit 302, an AD conversion unit 303, a monopulse DBF (Digital Beam Forming). ) Part 304.
The RF chip unit 302 amplifies the signal received by the antennas 301 a, 301 b, 301 c, and 301 d as subarray antennas, performs processing including signal down-conversion, and sends the signal to the AD conversion unit 303.
The AD conversion unit 303 performs analog-digital conversion on the signal sent from the RF chip unit, generates a digital signal, and sends it to the monopulse DBF 303 unit.
The monopulse DBF unit 304 estimates the arrival direction of the beam using the digital signal transmitted from the AD conversion unit 303. For further detailed operation, since a known technique is used, description thereof is omitted here.
Here, it is assumed that each of the antennas 301a, 301b, 301c, and 301d represents the subarray antenna 101 of the antenna device 100 according to the present embodiment. Here, four subarray antennas are used, but any number of subarray antennas may be used.
In the monopulse method, the output received by the subarray antenna is combined to create a sum signal and a difference signal, and the angle of the object is measured. Specifically, referring to FIG. 3, for example, when antennas 301a and 301b and antennas 301c and 301d are divided, the outputs of antennas 301a and 301b and the outputs of antennas 301c and 301d are combined in opposite phases, and a null is formed in the front direction. To do.
FIG. 4 shows an antenna device 100 according to the present embodiment actually realized by a post wall waveguide slot array. A feed line 401 and a package 402 are connected to the post wall waveguide slot array. The antenna device realized by the post wall waveguide slot array will be described later in detail with reference to FIG.
Here, it is assumed that the subarray antenna 101 is 301a, 301b, 301c, and 301d from the end. A signal received from each subarray antenna 101 is input to the package 302 through a feed line 301 connected to the feed section of each subarray antenna 101.
At this time, if the distance between the feed line 301 to the antenna 301a and the antenna 301b is shifted in length due to a manufacturing error, even if the outputs are combined so as to be in phase, between the antenna 301a and the antenna 301b, It is conceivable that a phase difference will occur up to each power feeding unit. However, even if a phase difference occurs, if the left and right are symmetrical, the same amount of phase difference is generated in the antenna 301c and the antenna 301d, so that they cancel each other, and the null in the front direction eventually shifts. It can be maintained without.

  According to the embodiment shown above, the interdigital structure is used to cause the subarray without causing physical interference such as the overlapping of the feeding ports of adjacent subarray antennas and without considering the size of the neighboring feeding ports. The distance between the antennas can be reduced. In addition, by adopting a structure in which the left and right subarray antenna groups are mirror images with respect to the central axis of the antenna device, the phase error appears symmetrically so that the null in the front direction is maintained, and the angle measurement is not affected by the manufacturing accuracy. The advantage is that accuracy is not impaired.

(First modification)
Next, a modification of the antenna device 100 according to the present embodiment shown in FIG. 1 is shown in FIG. This is because when the total number of sub-array antennas 101 is an even number, it is necessary to parallel the feed ports 104 of the two sub-array antennas 101 at the center in order to maintain a mirror image relationship, so the feed line 103 is offset. However, the adjacent power supply ports 104 may interfere with each other. Therefore, the two subarray antennas 101 closest to the central axis are extended so that the distance from the antenna element 102 closest to each power feeding unit is longer than the distances of the other subarray antennas 101. That is, power is supplied by extending the feed line 103 further to the outer side of the outermost subarray antenna 101 so that the feed ports 104 do not interfere with each other. That is, as shown in FIG. 5, the feed line 103 of the sub-array antenna 101 on the right side of the center forms a “L” shape. The two subarray antennas 101 at the center are not in an interdigital structure, but the remaining other subarray antennas 101 have an interdigital structure. Further, it is not always necessary to be outside the outermost subarray antenna 101, and the shortest distance between the power supply unit 104 and the central axis of the subarray antenna 101 closest to the central axis is the shortest distance from the central axis in the other power supply units 104. What is necessary is just to arrange | position at the longest distance compared with distance. Further, considering the area of the antenna at the time of manufacturing the antenna and other restrictions, the power feeding ports 104 may be arranged at positions where they do not interfere with each other.

  According to this modification, the left and right subarray antenna groups can maintain a mirror image relationship with respect to the central axis without interference between the two feeding ports 104 at the center of the antenna device 100.

(Specific example of the first modification)
FIG. 6 shows an example in which the first modified example is manufactured using a post-wall waveguide slot array. The post wall waveguide includes a dielectric substrate, a through hole 601, an antenna element 602, a power feeding port 603, and a matching pin 604.
The dielectric substrate is covered with a metal film made of a conductive metal material such as copper on the upper and lower surfaces on a material such as Teflon (registered trademark) or liquid crystal polymer.
The through-hole 601 is made of a metal member (called a through-hole member) that penetrates the dielectric substrate and short-circuits between the metal films. A through-wall waveguide that operates like a waveguide structure that is equivalently filled with a dielectric is formed by the through-hole row in which the through-holes 601 are aligned. The post wall waveguide shares a side surface corresponding to the narrow wall surface of the waveguide.
In the case of a slot antenna, the antenna element 602 is formed by opening a slot by etching. The post-wall waveguide slot array antenna operates as a slot array antenna with a waveguide filled with dielectric. The slot may be formed in various directions such as parallel, vertical, and oblique 45 degrees with respect to the tube axis direction in the post wall waveguide (corresponding to the direction parallel to the through-hole row forming the post wall waveguide). It is also possible to combine slots opened in various directions. The slots may be equally spaced or unequal. In the post wall waveguide slot array, a through hole may be provided in the post wall waveguide in addition to the through hole group forming the post wall waveguide.

An opening is formed in the power supply port 603 by etching. Further, the through hole row around the power supply port 603 has a step structure in which the row width is wider than the through hole row in the region where the slot is formed. However, the through-hole row around the power supply port 603 may not have a step structure, but may have the same width as the through-hole row in the region where the slot is formed.
The matching pin 604 is matched by penetrating a dielectric to prevent reflection loss in the antenna.
In order to form the first modification, the feeding ports 603 of the two sub-array antennas 101 at the center are routed and fed to the outside of the outermost sub-array antenna via the bend structure. The bend is formed as an L bend in FIG. 6, but a U bend may be used. There may be through holes located as alignment pins 604 in the L bend.

(Second modification)
In this embodiment, the subarray antenna 101 in the embodiment or the second embodiment is configured by a waveguide slot antenna, a dielectric waveguide slot antenna, a microstrip line patch antenna, a triplate line patch antenna, and a horn array. Since a known technique is used for manufacturing each antenna, a detailed description thereof is omitted here. Here, in particular, the arrangement of antenna elements in the subarray antenna will be described in detail with reference to FIGS. In FIG. 1, it is connected in series to a single feed line. However, as shown in FIG. 7, it may be a subarray antenna 701 in which the antenna elements 102 are branched from the feed line 702 toward one side. Further, as shown in FIG. 8, the arrangement of the subarray antenna 801 in which the antenna element 102 branches on both sides from the feed line 802 may be adopted. Further, as shown in FIG. 9, after branching from the feed line 902, eight antenna elements are provided for one branch from the feed line 902 by repeating the T branch three times and arranging the antenna element 102 at the end thereof. The subarray antenna 901 in which 102 is disposed may be used.
What is common to these subarray antennas 701, 801, and 901 in FIGS. 7 to 9 is that the antenna elements are arranged so as to maintain a mirror image relationship with respect to the central axis of the antenna device according to the present embodiment. Specifically, FIG. 10 shows an antenna element arrangement using the subarray antenna 701 of FIG. When the right side of the sub-array antenna 701 is arranged on the left side when viewed from the central axis, the sub-array antenna 701 arranged on the right side from the central axis is configured to branch to the left side.
According to the second modification described above, the antenna device according to the present embodiment can be realized with the antenna element arrangement corresponding to various antenna shapes.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows an example of the antenna device which concerns on this embodiment. The figure which shows another example of the antenna device which concerns on this embodiment. The block diagram which shows a radar apparatus. The figure which shows the electric power feeding line from a package to an antenna. The figure which shows the 1st modification of an antenna device. The figure which shows the example which manufactured the antenna apparatus with the post wall waveguide slot array antenna. The figure which shows the 1st another example of the antenna element arrangement | positioning of a subarray antenna. The figure which shows the 2nd another example of the antenna element arrangement | positioning of a subarray antenna. The figure which shows the 3rd another example of the antenna element arrangement | positioning of a subarray antenna. The figure which shows the antenna apparatus using the 1st another example of antenna element arrangement | positioning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Antenna apparatus, 101, 701, 801, 901 ... Subarray antenna, 102, 602 ... Antenna element, 103, 401, 702, 802, 902 ... Feed line, 104, 603 ... Feed port, 301a, 301b, 301c, 301d ... antenna, 302 ... RF chip, 303 ... AD converter, 304 ... monopulse DBF, 402 ... package, 601 ... through Hall, 604 ... alignment pin.

Claims (10)

A plurality of subarray antennas each including a plurality of antenna elements;
A plurality of power feeding sections connected to the end portions of the plurality of subarray antennas, one by one,
The plurality of subarray antennas are arranged in parallel on the same plane at intervals equal to or less than a free space wavelength, and are parallel to the plurality of subarray antennas on the same plane, and the total number of the plurality of subarray antennas is divided into two equal parts. An antenna device, wherein the subarray antenna groups are mirror images of each other with respect to a central axis that is divided into two subarray antenna groups.   Each of the feeding parts of the two subarray antennas closest to the central axis across the central axis has a longer distance from the antenna element closest to the feeding part than the distances of the other subarray antennas. The antenna device according to claim 1.   Each of the feeding portions of the two subarray antennas closest to the central axis across the central axis has the shortest distance between the feeding portion and the central axis being the longest compared to the shortest distance of the other feeding portions. The antenna device according to claim 1, wherein the antenna device is arranged at a distance.   In each of the two sub-array antenna groups, the plurality of second sub-array antennas adjacent to the first feeding unit included in the plurality of feeding units of the first sub-array antenna included in the plurality of sub-array antennas. The second feeding unit included in the feeding unit is connected to the end of the second subarray antenna that is farthest from the first feeding unit, and the feeding unit is interdigitally connected to each adjacent subarray antenna. The antenna device according to claim 1, wherein the antenna device is connected. A plurality of subarray antennas each including a plurality of antenna elements;
A plurality of power feeding sections for feeding power to the plurality of subarray antennas,
The plurality of subarray antennas are arranged so that the spacing between adjacent subarray antennas is equal to or less than a free space wavelength by paralleling the plurality of subarray antennas in parallel on the same plane with respect to the alignment direction of the plurality of antenna elements. The subarray antenna groups are in a mirror image relationship with respect to a central axis that is parallel to the plurality of subarray antennas and bisects the total number of the plurality of subarray antennas into two subarray antenna groups, In each of the two sub-array antenna groups, the fourth feed unit of the fourth sub-array antenna adjacent to the third feed unit of the third sub-array antenna that is the sub-array antenna closest to the central axis is the third feed unit. Connected to the end of the fourth sub-array antenna at the farthest distance from each of the sub- Antenna apparatus characterized by feeding part with respect to array antenna is connected to the interdigital.   Each of the feeding parts of the two subarray antennas closest to the central axis across the central axis has a longer distance from the antenna element closest to the feeding part than the distances of the other subarray antennas. 6. The antenna device according to claim 4, wherein the antenna device is characterized.   When the total number of the plurality of subarray antennas is an even number, the position where the third subarray antenna, which is the subarray antenna closest to the central axis, is connected to the third feeder in each of the subarray antenna groups. The third sub-array antenna is moved from the center of the power feeding unit toward the central axis in the direction of the central axis by a distance that is equal to or greater than a difference between the shortest distance and a half of the interval. The antenna device according to claim 1, wherein the antenna device is arranged to be offset in the direction of.   5. When the total number of the plurality of subarray antennas is an odd number, the other plurality of subarray antennas are arranged with the one subarray antenna in the center as the central axis. Item 6. The antenna device according to Item 5.   The plurality of antenna elements and the plurality of sub-array antennas are connected to a post-wall waveguide slot array antenna, a dielectric waveguide slot array antenna, a waveguide slot array antenna, a microstrip line patch antenna, a triplate line patch antenna, a horn array. It implement | achieves by any one of these, The antenna apparatus of any one of Claims 1-8 characterized by the above-mentioned. An antenna including a plurality of subarray antennas each including a plurality of antenna elements, and a plurality of power feeding units connected to one end of each of the plurality of subarray antennas;
An RF chip unit that performs processing including amplification of a signal received from the antenna and down-conversion to frequency-convert the signal to obtain a converted signal;
An analog-to-digital converter that performs analog-to-digital conversion on the converted signal to convert it to a digital signal;
A monopulse DBF unit for estimating the direction of arrival of the beam from the digital signal,
The plurality of subarray antennas are arranged in parallel on the same plane at intervals equal to or less than a free space wavelength, and are parallel to the plurality of subarray antennas on the same plane, and the total number of the plurality of subarray antennas is divided into two equal parts. A radar apparatus, wherein the sub-array antenna groups are mirror images of each other with respect to a central axis divided into two sub-array antenna groups.

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